Lift pump control systems may be used for a variety of purposes including vapor management, injection pressure control, temperature control, and lubrication. In one example, a lift pump supplies fuel to a higher pressure fuel pump that provides a high injection pressure for direct injectors in an internal combustion engine. The higher pressure fuel pump may provide the high injection pressure by supplying high pressure fuel to a fuel rail to which the direct injectors are coupled. A fuel pressure sensor may be disposed in the fuel rail to enable measurement of the fuel rail pressure, on which various aspects of engine operation may be based, such as fuel injection.
U.S. Pat. No. 7,640,916 discloses systems and methods for operating a fuel system in which a lift pump is intermittently, and not continuously, driven. Intermittent driving of the lift pump allows the energy expended in operating the lift pump to be reduced while maintaining the supply of adequate fuel pressures to a higher pressure fuel pump downstream of the lift pump. In some examples, driving of the lift pump may be initiated to maintain the pressure at the inlet of the higher pressure fuel pump above fuel vapor pressure, thereby maintaining the efficiency of the higher pressure fuel pump at a desired level. Conversely, driving of the lift pump may be ceased once the inlet pressure of the higher pressure fuel pump exceeds a predetermined threshold.
The inventors herein have recognized an issue with the approach identified above. Because the times at which initiation and cessation of lift pump actuation may be based on the required inlet pressure of the higher pressure fuel pump, the duration in which the lift pump is actuated may be excessive, unnecessarily increasing energy consumption. For example, the fuel volume pumped as a result of actuating the lift pump for a duration determined in this manner may be greater than a fuel volume required for operating an engine.
One approach that at least partially addresses the above issues includes a method of operating a fuel pump comprising iteratively reducing an on-duration of a low pressure fuel pump pulse, until a peak outlet pressure of the fuel pump decreases from a peak outlet pressure corresponding to a previous pulse, to identify a minimum pulse duration, and applying a pulse having the minimum pulse duration to the fuel pump.
In a more specific example, applying the pulse having the minimum pulse duration to the fuel pump causes the fuel pump to pump a desired fuel volume.
In another example, the on-duration of the fuel pump pulse is iteratively reduced until a duration for which the fuel pump outputs the peak outlet pressure falls below a threshold.
In this way, energy consumption of a fuel pump may be minimized while enabling the fuel pump to supply sufficient fuel volumes to an engine. Thus, the technical result is achieved by these actions.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Finally, the above explanation does not admit any of the information or problems were well known.